One of the many items I've been keeping an eye on this year is the relative ease (or otherwise) of scoring runs in the various ballparks around the country. The issue has been front and center here in Seattle, where never has so much tripe been spewed by so many ignorant buffoons about ballpark design and scoring. The issue in Seattle, of course, was going from a "hitter's dream" at the Kingdome, to a "pitcher's paradise" at Safeco Field. Lots of blather from the media blowhards, but very little hard information. The Seattle offense lost its way in the second half, but that was as much due to woeful hitting all around rather than the ballpark (although Safeco definitely suppressed offense).

Seattle is hardly the only place where ballpark myths exist, though. Camden Yards is another alleged "hitter's dream," if you listen to the inane droning of most baseball commentators.

To take some of the hot air out of the argument, we can calculate a little thing known as Park Factor. It's simply the number of runs scored per game in a given team's ballpark divided by the number of runs per game scored in that same team's road games. Simple, no?

It is simple, but it does foster it's own arguments. The numbers for a given ballpark can vary quite dramatically from one year to the next, causing arguments about whether it's caused by random variation or whether there's some deterministic reason for the variation.

One source of information that I haven't seen anyone examine is how well the home and road runs split between the teams themselves. With that in mind, I've compiled a table of park effects calculated the traditional way, and then for home teams and their opponents separately.

Team	Team RPG At Home	Team RPG On Road	Opp RPG At Home	Opp RPG On Road	Park Factor	Team Park Factor	Opp Park Factor	TPF/OPF
Cle	6.49	6.28	6.01	4.90	1.118	1.033	1.227	.842
Min	4.46	4.27	5.64	5.12	1.076	1.044	1.102	.948
Tex	6.03	5.94	5.66	5.21	1.049	1.015	1.088	.933
TB	4.76	4.95	6.09	5.41	1.047	.961	1.126	.853
Bos	5.59	4.97	4.46	4.64	1.046	1.124	.961	1.170
Bal	5.51	5.33	5.34	5.05	1.046	1.034	1.058	.977
Ana	4.38	4.62	5.57	4.90	1.045	.948	1.137	.834
KC	5.65	5.12	5.76	5.83	1.042	1.104	.988	1.117
Sea	5.60	5.26	5.60	5.86	1.008	1.066	.957	1.114
Oak	5.91	5.40	5.06	5.64	.994	1.094	.898	1.218
ChA	4.73	5.10	5.62	5.40	.986	.927	1.042	.889
Det	4.84	4.61	5.40	5.78	.985	1.050	.934	1.124
Tor	5.32	5.87	5.60	5.30	.978	.906	1.058	.857
NYY	5.07	6.43	3.99	5.37	.768	.789	.743	1.062
Average	5.31	5.30	5.41	5.31	1.011	1.003	1.019	.984

For purposes of this chart, "at home" always means the home park of the team to the left, and "on road" always means the road games of the team to the left.

If the proponents of runs scored park factor are correct, then there shouldn't be much difference between the park factor numbers for the home team and their opponents. There are, however, some big surprises. It wouldn't be too surprising if some teams showed a big swing in their favor in their own park. After all, the notion of tailoring your team to take advantage of your own ballpark is ages old. However, the evidence tends to point the other way.

Before I get into the details, maybe I should point out that the numbers don't all add up totally evenly because of that darned interleague play.

First of all, take a look at the grey center column. This is the traditional Park Factor, calculated as noted above. It shows that (this year) The Jake is quite the hitter's park, followed by the Metrodome, the Ballpark at Arlington and a host of mildly favorable hitter's parks. Seattle is a bit strange this year, as the home stats are split very closely between the Kingdome and the new ballpark, each with quite different characteristics.

Bottom of the pile is Yankee Stadium, a real depressant on runs scored (do they charge less there because of it?)

We could leave it at that, but why would we when there's so much more interesting information out there. Take a look at Anaheim, for instance, right in the middle of the pack, with an overall Park factor of 1.045. Based on just Angels runs, the park is substantial depressor, shaving about a quarter of a run per game from the Angels' scoring. If there's a home advantage, we'd expect to see the opponents lose a bit more than that. But no -- opponents absolutely love Edison Field, scoring almost three-quarters of a run more in Edison than they back in their home parks when facing the Angels.

A similar wild variation exists in Cleveland. The Indians score a smidge more at home than on the road, while opponents coming into the Jake core over a run per game more. So which is more correct? Is the Jake almost neutral, or is it a hitter's paradise? Other parks that seem to be a disadvantage to the home team are the Metrodome, Tropicana Field, The Ballpark at Arlington, Comiskey Park and SkyDome.

Note that Yankee Stadium shows a fairly small difference between the home team and opponents. The Yankees only score 79% as many runs at home as on the road, while their opponents only score 74% as much.

On the other hand, two ballparks that showed a huge home advantage this year are Boston and Oakland. Boston managed to score 12% more runs per game at home than on the road, while holding opponents to marginally lower numbers for a 17% advantage. Oakland, going one better, scored more at home but also held opponents to substantially less, for a total 22% advantage. No wonder their home record was so amazing. Was it due to deliberate ballclub tailoring? If so, why are there more teams in the AL that gave their opponents a relative advantage in their own parks? All curious questions.

There's a lot more meat to this debate, so I'd love to hear your views on the subject. Next up, I'll take a look at the NL, Coors Field and all.

That was not Dave Paisley on TV chanting "Ber-nie! Ber-nie!" during Game 1 of the Yankees-Rangers series. Ask him at drdjp@strikethree.com and he'll tell you that if he was going to help spell out "YANKS ROOL" he'd demand to be the "Y".

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